Devices of the type described herein are generally comprised of an implant portion which is anchored within bone and an abutment portion which supports the prosthesis and is connected to the implant. Important to the success of such devices is the rigid anchoring of the implant in the bone which is typically accomplished by providing a threaded hole in the bone to accommodate the implant. In this connection, the ability of the bone to accept and maintain the implant in situ is governed by a number of factors including resistance of the bone to fracturing both during drilling and insertion of the device and, importantly, transmission of loads acting on the device through the subsequently attached prothesis.
The specific problem of integrating teeth within the oral cavity by means other than superficial attachment has been addressed previously. One result is the proposal of Branemark as exemplified in Int. J. Oral Sur. 1981:10:387-416. In this proposal a generally cylindrical device is described which includes a number of connectable parts the majority of which are machined from substantially pure titanium.
Cylindrical implants, however, possess the disadvantage that they are unable to distribute evenly the forces derived from load bearing, e.g. during mastication, with the result that surrounding bone is unevenly stressed. It is desirable, therefore, to provide an implant which mitigates such undue stress so as to sustain generally the integrity of the bone surrounding the implant.
Thus it is an object of the present invention to provide a novel device for endosseous implantation which obviates or mitigates the above disadvantage.